Digging machine



Sept. 14, 1926. `,599,477

S. LAZAR DIGGING MACHINE Filed Nov. a', 1924 2 Shaets-Sheet 1 OO O I N VEN TOR, Stephen'flzar ATTORNEY.

Sept. 14 1926.

v 1,5,99,477 s. LAZAR DIGGING MACHINE Filed Nov. 8. ;924 2 Sheets-Sheet 2 INVENTOR,

Stephen Lazr A TTORNE Y.

.Patented Sept. 1 4, 1926.

UNITED sTArEs PATENT OFFICE.

DIGGING MACHINE.

Application filed November s, 1924.' seria'n 74s,585.

My inventio'n relates to a machine for digging circular holes in the ground.

The main objectof-ny invention is to' provide a power-driven digging machine which will speedily dig holes inthe ground to a depth suitable for setting posts, telephone poles, telegraph poles and the like.

Another object is to providea digging machine, of the character described, which' may be nountedon the rear end ofa motor truck for transportation from place to place and, which, when in position, m-ay be operated by the engine of the motor truck to dig holes to a predetermined depth.

Other objects and advantages will appear hereinafter, and while I show herewith and will describe a preferred form of Construction I desire it to be understood that I do not limit my invention" to such preferr'ed form, but that various changes and adaptations may be made therein without departing from the spirit of my invention as hereinatter claimed; y

Referring to thedrawings, which accompany this specification and form a part thereof,

Fig. 1 is a plan View of the preferred form of my digging machine, mounted on the rear end of a motor truck.

Fig. 2`is a View in side of elevation of the digging machine shown in Fig. 1 in its diggng position, part of its upper section being broken-away to save space. 4

Fig. 3 is' a View in rear elevation of the complete machine, with the boring element in Withdrawn position.

Fig. 4 isan enlarged vertical section on line 4--4 of Fig. 3, showing details of the upper end of themovable frame and feed shaft. i

Fig. 5 is an enlar ed vertical section on line 5--5 of Fig. 3, sowing further details of feeding parts.

Figs. 6 and 7 are enlarged vertical sections on lines 6-6 and 7-7 respectively of Fig.

3, showing details of movable frame and supporting frame. v Fig. 8 is a horizontal section on line 3--8 of Fig. 2, showing a plan View of the boring element. v

As shown in Figs. 1, 2 and 3 the digging machine consists of a supporting frame 10 e pivotall attached to the-rear end of a motor truc 11 and a movable frame 12 vertically slidable in supporting frame 10, said movable frame carrying the* digging elements of the machine. i

The supporting frame is a'rigid structure of metal bars approxim ately quare in plan and of a 'height somewhat'j'less than its width, havingits lower side-bars 13 extended forwardly as at 15 and fixed with pivot bolts 16 to the rear end of the auto truck frame 17. Braces 18,bolted to -the truck frame and tothe forward upper corners 19 of the supporting frame hold the latter in operative position. These braces are adapted to be loosened or removed, when the machine is not in use, so` that' the supporting frame, together with the movable frame,

may be swung onpivot bolts 16 forwardly and downwardly onto the motor truck, as indicated by arrow 20. A horizontal guide plate 22 is fixed across the top part of supporting framelO at ,its longitudinal center and a pair of parallel transverse angle-bars 23 'are Secured to side bars13 so that the center line of the space between them coincides vertically with the centerline of gude-plate 22. e

The movable frame 12 consists of a ve'rtical guide-red 24 and a vertical screwthreaded feed-shaft i 25, held in parallel spaced. relation to each other by an upper.

tie-bar 26 and a lower tie-bar 27, rigidly clamped on guide-rod 24: by nuts 28. i Feed shaft is .adapted to turn in bearings 29 formed on tie-bars 26 and 27, there being washers 30 adjacentthe hearings and spacing nuts 31 adjacent the washers with locknuts 32 in contact therewith. It extends through an aperture 33 in guide-plate 22 and through a nut 34: fixed' between angle bars 35 adjacent lower hearing 29 and an extension 36 therebelow on which is 'mounted a boring'head 37 having upwardly inclined radialzarms 38 to which are fixed detachable blades' 39, with serrated cutting edges 40, by means of screws 41. Guide-red '24 extends through an aperature 42 in 22 and through an aperture 43 n a lower guide plate 44 fixed to angle-bars 23, thus being slidably held in a vertical position. Boring head 37 with arms 38 and blades 39 constitute the boring elements of the machine. A beveled ear wheel 45, with a fixed ke 46 adapted to engage 'a spline 47 in fee -shaft 25 co-extensive wth the threacled portion thereof, is mounted on said Its lower end is provided with a collar ide plate feed-shaft 'ust above nut 34', so that when it is turne feed shaft 25 turns with it and feeds downwardly through nut 34 during the operation of digging. When turned in the reverse direction it feeds upwardly to withdraw the -digging elements from the g hole. A spacing sleeve 48 surrounding chain 54 runs over this sprocket wheel and.

over a drive sprocket 55 which is keyed to a drive-shaft 56 journaled in bearngs 57 on the under side of truck rame 17, said driveshaft being connected through gears 58 to the engine (not shown) of the motor truck.

A. relatively lar e sprocket wheel 59 is fixed on shaft a jacent gear-wheel 49 and upper and lower sprocket wheels 60 and 61 are mounted in 'vertical alignment therewith on pivot pins 62 and 63 respectively formed on extensions to tie-bars 26 and 27. 4

An endless sprocket chain 64, equ'ipped at in- 'tervals with pairs -of elevator buckets 65, attached-to its sides, runs over up er and lower sprocket wheels 60 and 61 an is held in engagement 'with one. side of sprocket wheel 59 by anidler sprocket 66 supported in a, bracket 67 on the top side of support-` ing frame 10 while it is held out of engagement with the other side of sprocket wheel 59 by a second idler sprocket 68, which turns on a shaft 69, having its ends fixed in side bars 13 of the supporting frame. Chain 64 and buckets constitute the elevating member of the machine which reciprocates vertically with the boring element.

The operation of my digging machine is e' as follows Drive shaft 56 is turned through gears 58 by the motor truck'engine and shaft 50 of 65, attached thereto, dip down into the loosened dirt adjacent the blades of the boring element and Carry it upwardly' throwing it out, as they pass over upper sprocket wheel 60, to the rear of the digging machine.

It should be noted that blades 39 are made in pairs having the serrations on the cutting edge of one in staggered relation to those of the others, so that the cutting eflect is made as great as possible.

It will be' seen that by driving the digger at a comparatively high speed the diggng of holes is rapidly accomplished by my machine. By reversing the direction of operation the diggng element is readily withdrawn from a finished hole preparatory to moving to the next position.

' Having thus illustrated and described my invention, I claim:

In a machine for digging post holes and the like, an elongated carrying frame, means to raise and lower said frame, a chain extending from end to end of said frame, sprocket wheels for said chain mounted on said frame, elevator buckets carried by said chain, diggng means comprising a boring bar extending longitudinally of said carry-` ing frame, a gear on said boring bar, a driving shaft, a drivng gear thereon meshing with said gear of the boring bar, and a sprocket wheel on said driving shaft, the

latter wheel directly engaging said sprocket chain at a point which permits the raising and lowering of said carrying rame. STEPHEN I AZAR 

